Alkali-containing catalyst formulations for low and medium temperature hydrogen generation

ABSTRACT

The invention is directed toward methods of using alkali-containing catalysts for generation of hydrogen-rich gas at temperatures of less than about 260° C. A WGS catalyst of the invention may have the following composition:  
     a) at least one of Pt, Ru, their oxides and mixtures thereof;  
     b) Na, its oxides or mixtures thereof; and optionally,  
     c) Li, its oxides and mixtures thereof.  
     The catalysts may be supported on a variety of catalyst support materials. The invention is also directed toward catalysts that exhibit both high activity and selectivity to hydrogen generation and carbon monoxide oxidation.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims benefit from earlier filed U.S.Provisional Application No. 60/434,707, filed Dec. 20, 2002, which isincorporated herein in its entirety by reference for all purposes. Thepresent application also incorporates by reference the PCT InternationalPatent Application No. ______ entitled “Alkali-Containing CatalystFormulations for Low and Medium Temperature Hydrogen Generation” namingas inventors Hagemeyer et al. (Attorney Docket No. 708000901PCT) filedon the same date as the present application.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to methods and catalysts to generate ahydrogen-rich gas at temperatures of less than about 260° C. from gasmixtures containing carbon monoxide and water, such as water-containingsyngas mixtures. More particularly, the invention includes methods ofusing alkali-containing catalysts for generation of hydrogen-rich gas attemperatures of less than about 260° C. The catalysts may be supportedon a variety of catalyst support materials. Catalysts of the inventionexhibit both high activity and selectivity to hydrogen generation andcarbon monoxide oxidation.

[0004] 2. Discussion of the Related Art

[0005] Numerous chemical and energy-producing processes require ahydrogen-rich composition (e.g. feed stream.) A hydrogen-rich feedstream is typically combined with other reactants to carry out variousprocesses. Nitrogen fixation processes, for example, produce ammonia byreacting feed streams containing hydrogen and nitrogen under highpressures and temperatures in the presence of a catalyst. In otherprocesses, the hydrogen-rich feed stream should not contain componentsdetrimental to the process. Fuel cells such as polymer electrodemembrane (“PEM”) fuel cells, produce energy from a hydrogen-rich feedstream. PEM fuel cells typically operate with a feed stream gas inlettemperature of less than 450° C. Carbon monoxide is excluded from thefeed stream to the extent possible to prevent poisoning of the electrodecatalyst, which is typically a platinum-containing catalyst. See U.S.Pat. No. 6,299,995.

[0006] One route for producing a hydrogen-rich gas is hydrocarbon steamreforming. In a hydrocarbon steam reforming process steam is reactedwith a hydrocarbon fuel, such as methane, iso-octane, toluene, etc., toproduce hydrogen gas and carbon dioxide. The reaction, shown below withmethane (CH₄), is strongly endothermic; it requires a significant amountof heat.

CH₄+2H₂O→4H₂+CO₂

[0007] In the petrochemical industry, hydrocarbon steam reforming ofnatural gas is typically performed at temperatures in excess of 900° C.Even for catalyst assisted hydrocarbon steam reforming the temperaturerequirement is often still above 700° C. See, for example, U.S. Pat. No.6,303,098. Steam reforming of hydrocarbons, such as methane, usingnickel- and gold-containing catalysts and temperatures greater than 450°C. is described in U.S. Pat. No. 5,997,835. The catalyzed process formsa hydrogen-rich gas, with depressed carbon formation.

[0008] One example of effective hydrocarbon steam reforming catalysts isthe Sinfelt compositions which are composed of Pt, a Group 11 metal, anda Group 8 to 10 metal. Group 11 metals include Cu, Ag and Au while Group8 to 10 metals include the other noble metals. These catalystformulations are well known in the promotion of hydrogenation,hydrogenolysis, hydrocracking, dealkylation of aromatics, and naphthareforming processes. See, for example, U.S. Pat. Nos. 3,567,625 and3,953,368. The application of catalysts based on the Sinfelt model tothe water gas shift (“WGS”) reaction, in particular at conditionssuitable for lower temperature WGS applications such as PEM fuel cells,has not been previously reported.

[0009] Purified hydrogen-containing feed streams have also been producedby filtering the gas mixture produced by hydrocarbon steam reformationthrough hydrogen-permeable and hydrogen-selective membranes. See, forexample, U.S. Pat. No. 6,221,117. Such approaches suffer from drawbacksdue to the complexity of the system and slow flow rates through themembranes.

[0010] Another method of producing a hydrogen-rich gas such as a feedstream starts with a gas mixture containing hydrogen and carbon monoxidewith the absence of any substantial amount of water. For instance, thismay be the product of reforming a hydrocarbon or an alcohol, andselectively removes the carbon monoxide from that gas mixture. Thecarbon monoxide can be removed by absorption of the carbon monoxideand/or by its oxidation to carbon dioxide. Such a process utilizing aruthenium based catalyst to remove and oxidize the carbon monoxide isdisclosed in U.S. Pat. No. 6,190,430.

[0011] The WGS reaction is another mechanism for producing ahydrogen-rich gas but from water (steam) and carbon monoxide. Anequilibrium process, the water gas shift reaction, shown below, convertswater and carbon monoxide to hydrogen and carbon dioxide, and viceversa.

[0012] Various catalysts have been developed to catalyze the WGSreaction. These catalysts are typically intended for use at temperaturesgreater than 450° C. and/or pressures above 1 bar. For instance, U.S.Pat. No. 5,030,440 relates to a palladium and platinum-containingcatalyst formulation for catalyzing the shift reaction at 550° C. to650° C. See also U.S. Pat. No. 5,830,425 for an iron/copper basedcatalyst formulation.

[0013] Catalytic conversion of water and carbon monoxide under water gasshift reaction conditions has been used to produce hydrogen-rich andcarbon monoxide-poor gas mixtures. Existing WGS catalysts, however, donot exhibit sufficient activity at a given temperature to reach or evenclosely approach thermodynamic equilibrium concentrations of hydrogenand carbon monoxide such that the product gas may subsequently be usedas a hydrogen feed stream. Specifically, existing catalyst formulationsare not sufficiently active at low temperatures, that is, below about450° C. See U.S. Pat. No. 5,030,440.

[0014] Platinum (Pt) is a well-known catalyst for both hydrocarbon steamreforming and water gas shift reactions. Under typical hydrocarbon steamreforming conditions, high temperature (above 850° C.) and high pressure(greater than 10 bar), the WGS reaction may occur post-reforming overthe hydrocarbon steam reforming catalyst due to the high temperature andgenerally unselective catalyst compositions. See, for instance, U.S.Pat. Nos. 6,254,807; 5,368,835; 5,134,109 and 5,030,440 for a variety ofcatalyst compositions and reaction conditions under which the water gasshift reaction may occur post-reforming.

[0015] Metals such as cobalt (Co), ruthenium (Ru), palladium (Pd),rhodium (Rh) and nickel (Ni) have also been used as WGS catalysts butare normally too active for the selective WGS reaction and causemethanation of CO to CH₄ under typical reaction conditions. In otherwords, the hydrogen produced by the water gas shift reaction is consumedas it reacts with the CO present in the presence of such catalysts toyield methane. This methanation reaction activity has limited theutility of metals such as Co, Ru, Pd, Rh and Ni as water gas shiftcatalysts.

[0016] A need exists, therefore, for a method to produce a hydrogen-richsyngas, and catalysts which are highly active and highly selective forboth hydrogen generation and carbon monoxide oxidation, especially atlow temperatures (e.g. below about 260° C.) to provide a hydrogen-richsyngas from a gas mixture containing hydrogen and carbon monoxide.

SUMMARY OF THE INVENTION

[0017] The invention meets the need for highly active and selectivecatalysts for the low temperature generation of hydrogen and theoxidation of carbon monoxide and to thereby provide a hydrogen-rich gas,such as a hydrogen-rich syngas, from a gas mixture of at least carbonmonoxide and water. Accordingly, the invention provides methods andcatalysts for producing a hydrogen-rich gas.

[0018] The invention is, in a first general embodiment, a method forproducing a hydrogen-rich gas (e.g., syngas) by contacting aCO-containing gas, such as a syngas mixture, with an alkali-containingwater gas shift catalyst in the presence of water at a temperature ofless than about 260° C. In the first general embodiment, the water gasshift catalyst comprises at least one of Pt, Ru, their oxides andmixtures thereof and Na, its oxides or mixtures thereof. In anothermethod of the first general embodiment, the water gas shift catalystcomprises at least one of Pt, Ru, their oxides and mixtures thereof, Na,its oxides or mixtures thereof and Li, its oxides or mixtures thereof.The catalyst may be supported on a carrier, for example, at least onemember selected from the group consisting of alumina, silica, zirconia,titania, ceria, magnesia, lanthania, niobia, zeolite, pervoskite, silicaclay, yttria, iron oxide and mixtures thereof. The method of theinvention is conducted at a temperature of less than about 260° C.

[0019] In a second general embodiment, the invention relates to thewater gas shift catalysts themselves—both supported and unsupportedcatalysts. The inventive water gas shift catalyst comprises, in a firstembodiment, at least one of Pt, Ru, their oxides and mixtures thereofand Na, its oxides or mixtures thereof. In another catalyst of thesecond general embodiment, the water gas shift catalyst comprises atleast one of Pt, Ru, their oxides and mixtures thereof, Na, its oxidesor mixtures thereof and Li, its oxides or mixtures thereof. The catalystmay be supported on a carrier comprising at least one member selectedfrom the group consisting of alumina, zirconia, titania, ceria,magnesia, lanthania, niobia, zeolite, pervoskite, silica clay, yttria,iron oxide and mixtures thereof.

[0020] In a third general embodiment, the invention is directed to theaforementioned water gas shift catalysts of the second generalembodiment in an apparatus for generating a hydrogen gas containingstream from a hydrocarbon or substituted hydrocarbon feed stream. Theapparatus further comprises, in addition to the WGS catalyst, a fuelreformer, a water gas shift reactor, and a temperature controller.

[0021] The following described preferred embodiments of the WGS catalystcan be used in each one of the first, second, and third generalembodiments or in specific, related embodiments (e.g., fuel cellreactors, fuel processors, hydrocarbon steam reformers.)

[0022] In one preferred embodiment the water gas shift catalystcomprises Pt, its oxides or mixtures thereof and Na, its oxides ormixtures thereof.

[0023] In a second preferred embodiment the water gas shift catalystcomprises Ru, its oxides or mixtures thereof and Na, its oxides ormixtures thereof.

[0024] In a third preferred embodiment the water gas shift catalystcomprises Pt, its oxides or mixtures thereof, Na, its oxides or mixturesthereof and Li, its oxides or mixtures thereof.

[0025] Another preferred embodiment for the water gas shift catalystcomprises Ru, its oxides or mixtures thereof, Na, its oxides or mixturesthereof and Li, its oxides or mixtures thereof

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The patent or application file contains at least one drawingexecuted in color. Copies of this patent or patent applicationpublication with color drawing(s) will be provided by the Office uponrequest and payment of the necessary fee.

[0027] The accompanying drawings, which are included to provide afurther understanding of the invention and are incorporated in andconstitute a part of this specification, illustrate preferredembodiments of the invention and together with the detailed descriptionserve to explain the principles of the invention. In the drawings:

[0028]FIGS. 1A-1D illustrate the process of producing a library testwafer and

[0029]FIGS. 1E-1G illustrate SpotFire plots of the CO conversion versusCO₂ production for the wafer under WGS conditions at varioustemperatures. The legend for FIG. 1A also applies to FIGS. 1B, 1C, and1D exclusively.

[0030]FIGS. 2A-2C illustrate the process of producing a library testwafer.

[0031]FIGS. 3A-3D illustrate the process of producing a library testwafer, and

[0032]FIGS. 3E and 3F illustrate SpotFire plots of the CO conversionversus CO₂ production for the wafer under WGS conditions at varioustemperatures. The legend for FIG. 3A also applies to FIGS. 3B, 3C, and3D exclusively.

[0033]FIG. 4 illustrates plots of CO concentration versus temperaturefor scaled-up catalyst samples under WGS conditions.

[0034]FIG. 5 illustrates plots of CO concentration versus temperaturefor scaled-up catalyst samples under WGS conditions.

[0035]FIGS. 6A-6F illustrate the compositional make-up of variousexemplary library test wafers. The legend for FIGS. 6A-6C applies onlyto FIGS. 6A-6C. The legend for FIGS. 6D-6F applies only to FIGS. 6D-6F.

[0036]FIG. 7A illustrates a representative plot of CO conversion versusCO₂ production for a prototypical library test wafer at varioustemperatures,

[0037]FIG. 7B illustrates the effect of catalyst selectivity andactivity versus the WGS mass balance, and

[0038]FIG. 7C illustrates the effect of temperature on catalystperformance under WGS conditions.

[0039]FIG. 8 illustrates plots of CO concentration versus temperaturefor scaled-up catalyst samples under WGS conditions.

DETAILED DESCRIPTION OF THE INVENTION

[0040] The invention relates to a method for producing a hydrogen-richgas, such as a hydrogen-rich syngas at low temperatures of less thanabout 260° C. According to the method a CO-containing gas such as asyngas contacts an alkali-containing water gas shift catalyst, in thepresence of water, preferably a stoichiometric excess of water toproduce a hydrogen-rich gas, such as a hydrogen-rich syngas. Thereaction pressure is preferably not more than about 10 bar. Theinvention also relates to a water gas shift catalyst itself and toapparatus such as water gas shift reactors and fuel processing apparatuscomprising such WGS catalysts.

[0041] A water gas shift catalyst according to the invention comprises:

[0042] a) at least one of Pt, Ru, their oxides and mixtures thereof,

[0043] b) Na, its oxides or mixtures thereof and optionally,

[0044] c) Li, its oxides or mixtures thereof.

[0045] The WGS catalyst may be supported on a carrier, such as any onemember or a combination of alumina, silica, zirconia, titania, ceria,magnesia, lanthania, niobia, yttria, and iron oxide.

[0046] The WGS catalysts of the invention comprise combinations of atleast two metals or metalloids, selected from the three groups asindicated above, in each and every possible permutation and combination,except as specifically and expressly excluded. Although particularsubgroupings of preferred combinations of metals or metalloids are alsopresented, the present invention is not limited to the particularlyrecited subgroupings.

[0047] Discussion regarding the particular function of variouscomponents of catalysts and catalyst systems is provided herein solelyto explain the advantage of the invention, and is not limiting as to thescope of the invention or the intended use, function, or mechanism ofthe various components and/or compositions disclosed and claimed. Assuch, any discussion of component and/or compositional function is made,without being bound by theory and by current understanding, unless andexcept such requirements are expressly recited in the claims. Generally,for example, and without being bound by theory, the metals of componenta), Pt and Ru, have activity as WGS catalysts. The metals or metalloidsof components b) and c) may themselves have activity as WGS catalystsbut function in combination with Pt and/or Ru to impart beneficialproperties to the catalyst of the invention.

[0048] Catalysts of the invention can catalyze the WGS reaction attemperatures of less than about 260° C., avoid or attenuate unwantedside reactions such as methanation reactions, as well as generate ahydrogen-rich gas, such as a hydrogen-rich syngas. The composition ofthe WGS catalysts of the invention and their use in WGS reactions arediscussed below.

[0049] 1. Definitions

[0050] Water gas shift (“WGS”) reaction: Reaction which produceshydrogen and carbon dioxide from water and carbon monoxide, and viceversa:

[0051] Generally, and unless explicitly stated to the contrary, each ofthe WGS catalysts of the invention can be advantageously applied both inconnection with the forward reaction as shown above (i.e., for theproduction of H₂), or alternatively, in connection with the reversereaction as shown above (i.e., for the production of CO). As such, thevarious catalysts disclosed herein can be used to specifically controlthe ratio of H₂ to CO in a gas stream.

[0052] Methanation reaction: Reaction which produces methane and waterfrom a carbon source, such as carbon monoxide or carbon dioxide, andhydrogen:

[0053] “Syngas” (also called synthesis gas): Gaseous mixture comprisinghydrogen (H₂) and carbon monoxide (CO) which may also contain other gascomponents such as carbon dioxide (CO₂), water (H₂O), methane (CH₄) andnitrogen (N₂).

[0054] LTS: Refers to “low temperature shift” reaction conditions wherethe reaction temperature is less than about 250° C., preferably rangingfrom about 150° C. to about 250° C.

[0055] MTS: Refers to “medium temperature shift” reaction conditionswhere the reaction temperature ranges from about 250° C. to about 350°C.

[0056] HTS: Refers to “high temperature shift” reaction conditions wherethe reaction temperature is more than about 350° C. and up to about 450°C.

[0057] Hydrocarbon: Compound containing hydrogen, carbon, and,optionally, oxygen. The Periodic Table of the Elements is based on thepresent IUPAC convention, thus, for example, Group 11 comprises Cu, Agand Au. (See http://www.iupac.org dated May 30, 2002.)

[0058] As discussed herein, the catalyst composition nomenclature uses adash (i.e., “-”) to separate catalyst component groups where a catalystmay contain one or more of the catalyst components listed for eachcomponent group, brackets (i.e., “{ }”) are used to enclose the membersof a catalyst component group, “{two of . . . }” is used if two or moremembers of a catalyst component group are required to be present in acatalyst composition, “blank” is used within the “{ }” to indicate thepossible choice that no additional element is added, and a slash (i.e.,“/”) is used to separate supported catalyst components from theirsupport material, if any. Additionally, the elements within catalystcomposition formulations include all possible oxidation states,including oxides, or salts, or mixtures thereof.

[0059] Using this shorthand nomenclature in this specification, forexample, “Pt-{Rh, Ni}-{Na, K, Fe, Os}/ZrO₂” would represent catalystcompositions containing Pt, one or more of Rh and Ni, and one or more ofNa, K, Fe, and Os supported on ZrO₂; all of the catalyst elements may bein any possible oxidation state, unless explicitly indicated otherwise.“Pt-Rh-Ni-{two of Na, K, Fe, Os}” would represent a supported orunsupported catalyst composition containing Pt, Rh, and Ni, and two ormore of Na, K, Fe, and Os. “Rh-{Cu, Ag, Au}-{Na, K, blank}/TiO₂” wouldrepresent catalyst compositions containing Rh, one or more of Cu, Ag andAu, and, optionally, and one of Na or K supported on TiO₂.

[0060] 2. WGS Catalyst

[0061] A water gas shift catalyst of the invention comprises:

[0062] a) at least one of Pt, Ru, their oxides and mixtures thereof;

[0063] b) Na, its oxides or mixtures thereof; and optionally,

[0064] c) Li, its oxides or mixtures thereof.

[0065] The catalysts of the invention may be supported on carriers.Suitable carriers for supported catalysts are discussed below.

[0066] The catalyst components are typically present in a mixture of thereduced or oxide forms; typically, one of the forms will predominate inthe mixture. A WGS catalyst of the invention may be prepared by mixingthe metals and/or metalloids in their elemental forms or as oxides orsalts to form a catalyst precursor. This catalyst precursor mixturegenerally undergoes a calcination and/or reductive treatment, which maybe in-situ (within the reactor), prior to use as a WGS catalyst. Withoutbeing bound by theory, the catalytically active species are generallyunderstood to be species which are in the reduced elemental state or inother possible higher oxidation states. The catalyst precursor speciesare believed to be substantially completely converted to thecatalytically active species by the pre-use treatment. Nonetheless, thecatalyst component species present after calcination and/or reductionmay be a mixture of catalytically active species such as the reducedmetal or other possible higher oxidation states and uncalcined orunreduced species depending on the efficiency of the calcination and/orreduction conditions.

[0067] A. Catalyst Compositions

[0068] As discussed above, one embodiment of the invention is analkali-containing catalyst for catalyzing the water gas shift reaction(or its reverse reaction). The catalysts have been found to exhibit highLTS and MTS activity, with activities at temperatures as low as about200° C. According to the invention, a WGS catalyst may have thefollowing composition:

[0069] a) at least one of Pt, Ru, their oxides and mixtures thereof;

[0070] b) Na, its oxides or mixtures thereof; and optionally,

[0071] c) Li, its oxides and mixtures thereof.

[0072] The amount of each component present in a given catalystaccording to the present invention may vary depending on the reactionconditions under which the catalyst is intended to operate. Generally,the Pt or Ru component may be present in an amount ranging from about0.01 wt. % to about 10 wt. %, preferably about 0.01 wt. % to about 2 wt.%, and more preferably about 0.05 wt. % to about 0.5 wt. %. The Nacomponent may be present in a range ranging from about 0.1 wt. % toabout 20 wt. %, preferably about 1 wt. % to about 15 wt. %. The Licomponent may be present, typically, in amounts ranging from about 0.05wt. % to about 20 wt. %, preferably about 0.1 wt. % to about 15 wt. %.

[0073] The above weight percentages are calculated on the total weightof the catalyst component in its final state in the catalyst compositionafter the final catalyst preparation step (i.e., the resulting oxidationstate or states) with respect to the total weight of all catalystcomponents plus the support material, if any. The presence of a givencatalyst component in the support material and the extent and type ofits interaction with other catalyst components may effect the amount ofa component needed to achieve the desired performance effect.

[0074] Other WGS catalysts which embody the invention are listed below.Utilizing the shorthand notation discussed above, where each metal maybe present in its reduced form or in a higher oxidation state, thefollowing compositions are examples of preferred catalyst compositions:

[0075] {Pt, Ru}-Na;

[0076] {Pt, Ru}-Na-Li;

[0077] Pt-Na;

[0078] Pt-Li;

[0079] Pt-Na-Li; and

[0080] Ru-Na-Li.

[0081] B. Catalyst Component a): Pt, Ru

[0082] A first component in a catalyst of the invention is Pt or Ru,component a). Each one of these metal components may be present in acombination of its reduced form and its oxide. Catalysts of theinvention may contain mixtures of these metals. Pt and Ru each catalyzethe WGS reaction.

[0083] C. Catalyst Components b) and c): Na and Li, Respectively

[0084] The WGS catalysts of the invention contain at least two metals ormetalloids. In addition to component a), discussed above, a WGS catalystof the invention contains metals or metalloids which, when used incombination with Pt and/or Ru, function to impart beneficial propertiesto the catalyst formulation. A catalyst of the invention, then, furthercomprises Na, its oxides or mixtures thereof, component b); and,optionally, Li, its oxides or mixtures thereof, component c).

[0085] Sodium hydroxide (NaOH), sodium carbonate (Na₂CO₃), sodiumhydrogen carbonate (NaHCO₃) and sodium formate (NaOOCH) have beenidentified as suitable Na precursors. High Na loadings were found to bebeneficial for LTS activity; typically Na loadings in the range of about0.1 wt. % to about 20 wt. % are preferred, more preferred are Naloadings in the range of between about 1 wt. % and about 15 wt. %. TheNaOH precursor may reversibly react with CO₂ present in the gas streamto form sodium hydrogen carbonate (NaHCO₃) or may react with CO presentin the gas stream.

[0086] Lithium hydroxide (LiOH) is an example of a suitable Liprecursor.

[0087] The Na and optional Li components of the catalysts of theinvention form a synergistic pair that, in combination with either orboth of Pt or Ru, exhibits high WGS activity at LTS but also highselectivity at MTS. Li, in combination with either or both of Pt or Ru,was found to be generally less active than Na at LTS.

[0088] Preferred carriers include, for instance, zirconia, alumina andsilica. In one embodiment, the alumina is doped with Zr. Preferredsupported catalysts include, for example, Pt—Na/ZrO₂, Pt—Na—Li/ZrO₂,Ru—Na/ZrO₂, Ru—Na—Li/ZrO₂, Pt—Na/Al₂O₃, Pt—Na—Li/Al₂O₃, Ru—Na/Al₂O₃,Pt—Na/SiO₂ and Ru—Na—Li/SiO₂. For the alumina supported catalysts,γ-Al₂O₃ is preferred.

[0089] D. Functional Classification of Catalyst Components

[0090] Without limiting the scope of the invention, discussion of thefunctions of the various catalyst components is offered, along with atemplate for composing catalyst compositions according to the invention.The following classification of catalyst components will direct one ofskill in the art in the selection of various catalyst components toformulate WGS catalyst compositions according to the present inventionand depending on the reaction conditions of interest.

[0091] Furthermore, according to the invention, there are severalclasses of catalyst components and metals which may be incorporated intoa water gas shift catalyst. Hence, the various elements recited ascomponents in any of the described embodiments may be included in anyvarious combination and permutation to achieve a catalyst compositionthat is coarsely or finely tuned for a specific application (e.g.including for a specific set of conditions, such as, temperature,pressure, space velocity, catalyst precursor, catalyst loading, catalystsurface area/presentation, reactant flow rates, reactant ratios, etc.).In some cases, the effect of a given component may vary with theoperating temperature for the catalyst. These catalyst components mayfunction as, for instance, activators or moderators depending upon theireffect on the performance characteristics of the catalyst. For example,if greater activity is desired, an activator may be incorporated into acatalyst, or a moderator may be replaced by at least one activator or,alternatively, by at least one moderator one step further up the“activity ladder.” An “activity ladder” ranks secondary or addedcatalyst components, such as activators or moderators, in order of themagnitude of their respective effect on the performance of a principalcatalyst. Conversely, if WGS selectivity of a catalyst needs to beincreased (e.g., decrease the occurrence of the competing methanationreaction), then either an activator may be removed from the catalyst or,alternatively, the current moderator may be replaced by at least onemoderator one step down the “activity ladder.” The function of thesecatalyst component may be further described as “hard” or “soft”depending on the relative effect obtained by incorporating a givencomponent into a catalyst. The catalyst components may be metals,metalloids, or non-metals.

[0092] For instance, typically, a WGS catalyst according to theinvention suitable for use under LTS conditions employs activators andmay only be minimally moderated, if at all, because activation isgenerally the important parameter to be considered under LTS conditions.Such LTS catalysts also may preferably employ high surface area carriersto enhance catalyst activity. Conversely, WGS catalysts used in HTSconditions may benefit from the catalyst being moderated becauseselectivity and methanation are parameters to be considered. Such HTScatalysts may use, for example, low surface area carriers. Accordingly,operating temperature may be considered in selecting a WGS catalystaccording to the present invention for a particular operatingenvironment.

[0093] Activators according to the present invention may include Ru andCo as active and selective WGS-promoting metals. Re and Pd are examplesof metals that are moderately active but not very selective and alsopromote methanation. Ir has also been observed to have a slightmoderating or activating function, depending on the presence of othercounter metals. Other activators may include, but are not limited to,Ti, Zr, V, Mo, La, Ce, Pr and Eu. Ce may be the most active rare earthmetal for activating the WGS reaction. La, Pr, Sm and Eu may also beactive, particularly at lower temperatures. For HTS, Pr and Sm arepreferred soft moderators enhancing selectivity without sacrificing muchactivity. For LTS, La and Eu may be useful activators. In general, alllanthanides, other than Ce, show comparable performance and tend tomoderate rather than activate noble metal containing catalyst systems. Yis a highly selective moderator for HTS systems whereas La and Eu areactive and comparable to Ce for LTS. La is only slightly moderating whendoping Ce and may therefore be used to adjust the selectivity of Cecontaining catalyst systems.

[0094] Catalyst components that are slightly moderating and highlyselective over a relatively broad temperature range (e.g., a temperaturerange of at least about 50° C., preferably at least about 75° C., andmost preferably a temperature range of at least about 100° C.), wheresuch temperature range is included within the overall preferredtemperature ranges of up to about 450° C., include Y, Mo, Fe, Pr and Sm;these tend to be selective but not very active at low temperatures,about 250° C. The redox dopants Mo, Fe, Pr and Sm generally loseactivity with increasing pre-reduction temperatures while Fe becomesmoderately active on its own at high WGS reaction temperatures.

[0095] Moderators may also include Cu, Ag, Au, Cd, In, Ge, Sn, Sb andTe. Typically, for moderators to exert a moderating function, theyshould be substantially in the reduced or metallic state. Ge alloyedwith Sn is an example of an alloy that was found to be highly active,even for low temperature systems, when in the fully oxidized state, thatis, when treated at a pre-reduction temperature of about 300° C. whichreduces the noble metals (such as Pt, Rh or Pd) selectively but does notchange the active oxidized state of the redox dopants in a catalystcomposition.

[0096] E. Supports

[0097] The support or carrier may be any support or carrier used withthe catalyst which allows the water gas shift reaction to proceed. Thesupport or carrier may be a porous, adsorptive, high surface areasupport with a surface area of about 25 to about 500 m²/g. The porouscarrier material may be relatively inert to the conditions utilized inthe WGS process, and may include carrier materials that havetraditionally be utilized in hydrocarbon steam reforming processes, suchas, (1) activated carbon, coke, or charcoal; (2) silica or silica gel,silicon carbide, clays, and silicates including those syntheticallyprepared and naturally occurring, for example, china clay, diatomaceousearth, fuller's earth, kaolin, etc.; (3) ceramics, porcelain, bauxite;(4) refractory inorganic oxides such as alumina, titanium dioxide,zirconium oxide, magnesia, etc.; (5) crystalline and amorphousaluminosilicates such as naturally occurring or synthetically preparedmordenite and/or faujasite; and, (6) combinations of these groups.

[0098] When a WGS catalyst of the invention is a supported catalyst, thesupport utilized may contain one or more of the metals (or metalloids)of the catalyst. The support may contain sufficient or excess amounts ofthe metal for the catalyst such that the catalyst may be formed bycombining the other components with the support. Examples of suchsupports include ceria which can contribute cerium, Ce, to a catalyst,or iron oxide which can contribute iron, Fe. When such supports are usedthe amount of the catalyst component in the support typically may be farin excess of the amount of the catalyst component needed for thecatalyst. Thus the support may act as both an active catalyst componentand a support material for the catalyst. Alternatively, the support mayhave only minor amounts of a metal making up the WGS catalyst such thatthe catalyst may be formed by combining all desired components on thesupport.

[0099] Carrier screening with catalysts containing Pt as the only activenoble metal revealed that a water gas shift catalyst may also besupported on a carrier comprising alumina, silica, zirconia, titania,ceria, magnesia, lanthania, niobia, zeolite, pervoskite, silica clay,yttria and iron oxide. Perovskite may also be utilized as a support forthe inventive catalyst formulations.

[0100] Zirconia, alumina and silica may be supports for the presentinvention and provide high activity for the WGS reaction. Preferably,zirconia is in the monoclinic phase. Highly pure ceria was found toactivate Pt in LTS conditions more than cerias doped with additives.Niobia, yttria and iron oxide carriers provide high selectivity but arealso less active which is believed to be due to a lack of surface area.Pt on magnesia carriers formulated to have high surface areas(approximately 100 m²/g) exhibit high selectivity but also exhibitactivity which decreases rapidly with falling reaction temperature.

[0101] Iron, yttrium, and magnesium oxides may be utilized as primarylayers on zirconia carriers to provide both higher surface area and lowmoderator concentration.

[0102] In general, alumina has been found to be an active butunselective carrier for Pt only containing WGS catalysts. However, theselectivity of gamma alumina may be improved by doping with Zr and/or Coor one of the rare earth elements, such as, for example, La and Ce. Thisdoping may be accomplished by addition of the oxides or other salts suchas nitrates, in either liquid or solid form, to the alumina. Otherpossible dopants to increase the selectivity include redox dopants, suchas for instance, Re, Mo, Fe and basic dopants. Preferred is anembodiment of gamma alumina combined with Zr and/or Co which exhibitsboth high activity and selectivity over a broad temperature range.

[0103] High surface area aluminas, such as gamma-, delta- ortheta-alumina are preferred alumina carriers. Other alumina carriers,such as mixed silica alumina, sol-gel alumina, as well as sol-gel orco-precipitated alumina-zirconia carriers may be used. Alumina typicallyhas a higher surface area and a higher pore volume than carriers such aszirconia and offers a price advantage over other more expensivecarriers.

[0104] F. Methods of Making a WGS Catalyst

[0105] As set forth above, a WGS catalyst of the invention may beprepared by mixing the metals and/or metalloids in their elemental formsor as oxides or salts to form a catalyst precursor, which generallyundergoes a calcination and/or reductive treatment. Without being boundby theory, the catalytically active species are generally understood tobe species which are in the reduced elemental state or in other possiblehigher oxidation states.

[0106] The WGS catalysts of the invention may be prepared by any wellknown catalyst synthesis processes. See, for example, U.S. Pat. Nos.6,299,995 and 6,293,979. Spray drying, precipitation, impregnation,incipient wetness, ion exchange, fluid bed coating, physical or chemicalvapor deposition are just examples of several methods that may beutilized to make the present WGS catalysts. Preferred approaches,include, for instance, impregnation or incipient wetness. The catalystmay be in any suitable form, such as, pellets, granular, bed, ormonolith. See also co-pending U.S. patent application Ser. No. ______entitled “Methods For The Preparation Of Catalysts For HydrogenGeneration” to Hagemeyer et al. (Attorney Docket No. 7080-011-01), filedon the same date as the present application, for further details onmethods of catalyst preparation and catalyst precursors. The completedisclosure of the above mentioned application and all other referencescited herein are incorporated herein in their entireties for allpurposes.

[0107] The WGS catalyst of the invention may be prepared on a solidsupport or carrier material. Preferably, the support or carrier is, oris coated with, a high surface area material onto which the precursorsof the catalyst are added by any of several different possibletechniques, as set forth above and as known in the art. The catalyst ofthe invention may be employed in the form of pellets, or on a support,preferably a monolith, for instance a honeycomb monolith.

[0108] Catalyst precursor solutions are preferably composed of easilydecomposable forms of the catalyst component in a sufficiently highenough concentration to permit convenient preparation. Examples ofeasily decomposable precursor forms include the nitrate, amine, andoxalate salts. Typically chlorine containing precursors are avoided toprevent chlorine poisoning of the catalyst. Solutions can be aqueous ornon-aqueous solutions. Exemplary non-aqueous solvents can include polarsolvents, aprotic solvents, alcohols, and crown ethers, for example,tetrahydrofuran and ethanol. Concentration of the precursor solutionsgenerally may be up to the solubility limitations of the preparationtechnique with consideration given to such parameters as, for example,porosity of the support, number of impregnation steps, pH of theprecursor solutions, and so forth. The appropriate catalyst componentprecursor concentration can be readily determined by one of ordinaryskill in the art of catalyst preparation.

[0109] Li—The acetate, carbonate, hydroxide, nitrate and formate saltsare possible catalyst precursors for lithium.

[0110] Na—Sodium acetate, alkoxides including methoxide, ethoxide, andpropoxide, bicarbonate, carbonate, citrate, formate, hydroxide, nitrate,nitrite, oxalate and lactate may be used to prepare WGS catalysts of theinvention.

[0111] Ru—Ru nitrosyl nitrate, Ru(NO)(NO₃)₃ (Aldrich), potassiumruthenium oxide, K₂RuO₄ ⁻H₂O, potassium perruthenate, KRuO₄, rutheniumnitrosyl acetate, Ru(NO)(OAc)₃, and tetrabutylammonium perruthenate,NBu₄RuO₄, are all possible ruthenium metal catalyst precursors. ANMe₄Ru(NO)(OH)₄ solution can be prepared by dissolving Ru(NO)(OH)₃ (0.1M) (H. C. Starck) in NMe₄OH (0.12M) at 80° C. which produces a cleardark red-brown 0.1M Ru solution useful as a catalyst precursor solution.

[0112] Pt—Platinum containing catalyst compositions may be prepared byusing any one of a number of precursor solutions, such as,Pt(NH₃)₄(NO₃)₂ (Aldrich, Alfa, Heraeus, or Strem), Pt(NH₃)₂(NO₂)₂ innitric acid, Pt(NH₃)₄(OH)₂ (Alfa), K₂Pt(NO₂)₄, Pt(NO₃)₂, PtCl₄ andH₂PtCl₆ (chloroplatinic acid). Pt(NH₃)₄(HCO₃)₂, Pt(NH₃)₄(HPO₄),(NMe₄)₂Pt(OH)₆, H₂Pt(OH)₆, K₂Pt(OH)₆, Na₂Pt(OH)₆ and K₂Pt(CN)₆ are alsopossible choices along with Pt oxalate salts, such as K₂Pt(C₂O₄)₂. ThePt oxalate salts may be prepared from Pt(NH₃)₄(OH)₂ which is reactedwith 1M oxalic acid solution to produce a clear, colorless solution ofthe desired Pt oxalate salts.

[0113] 3. Producing a Hydrogen-Rich Gas, such as, a Hydrogen-Rich Syngas

[0114] The invention also relates to a method for producing ahydrogen-rich gas, such as a hydrogen-rich syngas. An additionalembodiment of the invention may be directed to a method of producing aCO-depleted gas, such as a CO-depleted syngas.

[0115] A CO-containing gas, such as a syngas, contacts with analkali-containing water gas shift catalyst in the presence of wateraccording to the method of the invention. The reaction preferably mayoccur at a temperature of less than about 260° C. to produce ahydrogen-rich gas such as a hydrogen-rich syngas.

[0116] A method of the invention may be utilized over a broad range ofreaction conditions. Preferably, the method is conducted at a pressureof no more than about 75 bar, preferably at a pressure of no more thanabout 50 bar to produce a hydrogen-rich syngas. Even more preferred isto have the reaction occur at a pressure of no more than about 25 bar,or even no more than about 15 bar, or not more than about 10 bar.Especially preferred is to have the reaction occur at, or aboutatmospheric pressure. Preferably, the reaction occurs at a temperatureof less than about 260° C. Space velocities may range from about 1 hr⁻¹up to about 1,000,000 hr⁻¹. Feed ratios, temperature, pressure and thedesired product ratio are factors that would normally be considered byone of skill in the art to determine a desired optimum space velocityfor a particular catalyst formulation.

[0117] 4. Fuel Processor Apparatus

[0118] The invention further relates to a fuel processing system forgeneration of a hydrogen-rich gas from a hydrocarbon or substitutedhydrocarbon fuel. Such a fuel processing system would comprise, forexample, a fuel reformer, a water gas shift reactor and a temperaturecontroller.

[0119] The fuel reformer would convert a fuel reactant stream comprisinga hydrocarbon or a substituted hydrocarbon fuel to a reformed productstream comprising carbon monoxide and water. The fuel reformer maytypically have an inlet for receiving the reactant stream, a reactionchamber for converting the reactant stream to the product stream and anoutlet for discharging the product stream.

[0120] The fuel processor would also comprise a water gas shift reactorfor effecting a water gas shift reaction at a temperature of less thanabout 260° C. This water gas shift reactor may comprise an inlet forreceiving a water gas shift feed stream comprising carbon monoxide andwater from the product stream of the fuel reformer, a reaction chamberhaving a water gas shift catalyst as described herein located thereinand an outlet for discharging the resulting hydrogen-rich gas. The watergas shift catalyst would preferably be effective for generating hydrogenand carbon dioxide from the water gas shift feed stream.

[0121] The temperature controller may be adapted to maintain thetemperature of the reaction chamber of the water gas shift reactor at atemperature of less than about 300° C., preferably at a temperature ofless than about 260° C.

[0122] 5. Industrial Applications

[0123] Syngas is used as a reactant feed in number of industrialapplications, including for example, methanol synthesis, ammoniasynthesis, oxoaldehyde synthesis from olefins (typically in combinationwith a subsequent hydrogenation to form the corresponding oxoalcohol),hydrogenations and carbonylations. Each of these various industrialapplications preferably includes a certain ratio of H₂ to CO in thesyngas reactant stream. For methanol synthesis the ratio of H₂:CO ispreferably about 2:1. For oxosynthesis of oxoaldehydes from olefins, theratio of H₂:CO is preferably about 1:1. For ammonia synthesis, the ratioof H₂ to N₂ (e.g., supplied from air) is preferably about 3:1. Forhydrogenations, syngas feed streams that have higher ratios of H₂:CO arepreferred (e.g., feed streams that are H₂ enriched, and that arepreferably substantially H₂ pure feed streams). Carbonylation reactionsare preferably effected using feed streams that have lower ratios ofH₂:CO (e.g., feed streams that are CO enriched, and that are preferablysubstantially CO pure feed streams).

[0124] The WGS catalysts of the present invention, and the methodsdisclosed herein that employ such WGS catalysts, can be appliedindustrially to adjust or control the relative ratio H₂:CO in a feedstream for a synthesis reaction, such as methanol synthesis, ammoniasynthesis, oxoaldehyde synthesis, hydrogenation reactions andcarbonylation reactions. In one embodiment, for example, a syngasproduct stream comprising CO and H₂ can be produced from a hydrocarbonby a reforming reaction in a reformer (e.g., by steam reforming of ahydrocarbon such as methanol or naphtha). The syngas product stream canthen be fed (directly or indirectly after further downstream processing)as the feed stream to a WGS reactor, preferably having a temperaturecontroller adapted to maintain the temperature of the WGS reactor at atemperature of about 450° C. or less during the WGS reaction (or atlower temperatures or temperature ranges as described herein inconnection with the catalysts of the present invention). The WGScatalyst(s) employed in the WGS reactor are preferably selected from oneor more of the catalysts and/or methods of the invention. The feedstream to the WGS reactor is contacted with the WGS catalyst(s) underreaction conditions effective for controlling the ratio of H₂:CO in theproduct stream from the WGS reactor (i.e., the “shifted product stream”)to the desired ratio for the downstream reaction of interest (e.g.,methanol synthesis), including to ratios described above in connectionwith the various reactions of industrial significance. As a non-limitingexample, a syngas product stream from a methane steam reformer willtypically have a H₂:CO ratio of about 6:1. The WGS catalyst(s) of thepresent invention can be employed in a WGS reaction (in the forwarddirection as shown above) to further enhance the amount of H₂ relativeto CO, for example to more than about 10:1, for a downstreamhydrogenation reaction. As another example, the ratio of H₂:CO in such asyngas product stream can be reduced by using a WGS catalyst(s) of thepresent invention in a WGS reaction (in the reverse direction as shownabove) to achieve or approach the desired 2:1 ratio for methanolsynthesis. Other examples will be known to a person of skill in the artin view of the teachings of the present invention.

[0125] A person of skill in the art will understand and appreciate thatwith respect to each of the preferred catalyst embodiments as describedin the preceding paragraphs, the particular components of eachembodiment can be present in their elemental state or in one or moreoxide states or mixtures thereof.

[0126] Although the foregoing description is directed to the preferredembodiments of the invention, it is noted that other variations andmodifications will be apparent to those skilled in the art, and whichmay be made without departing from the spirit or scope of the invention.

EXAMPLES

[0127] General

[0128] Small quantity catalyst composition samples are generallyprepared by automated liquid dispensing robots (Cavro ScientificInstruments) on flat quartz test wafers.

[0129] Generally, supported catalysts are prepared by providing acatalyst support (e.g. alumina, silica, titania, etc.) to the wafersubstrate, typically as a slurry composition using a liquid-handlingrobot to individual regions or locations on the substrate or bywash-coating a surface of the substrate using techniques known to thoseof skill in the art, and drying to form dried solid support material onthe substrate. Discrete regions of the support-containing substrate arethen impregnated with specified compositions intended to operate ascatalysts or catalyst precursors, with the compositions comprisingmetals (e.g. various combinations of transition metal salts). In somecircumstances the compositions are delivered to the region as a mixtureof different metal-containing components and in some circumstances(additionally or alternatively) repeated or repetitive impregnationsteps are performed using different metal-containing precursors. Thecompositions are dried to form supported catalyst precursors. Thesupported catalyst precursors are treated by calcining and/or reducingto form active supported catalytic materials at discrete regions on thewafer substrate.

[0130] Bulk catalysts may also be prepared on the substrate. Suchmulti-component bulk catalysts are purchased from a commercial sourceand/or are prepared by precipitation or co-precipitation protocols, andthen optionally treated—including mechanical pretreatment (grinding,sieving, pressing). The bulk catalysts are placed on the substrate,typically by slurry dispensing and drying, and then optionally furtherdoped with additional metal-containing components (e.g. metal saltprecursors) by impregnation and/or incipient wetness techniques to formbulk catalyst precursors, with such techniques being generally known tothose of skill in the art. The bulk catalyst precursors are treated bycalcining and/or reducing to form active bulk catalytic materials atdiscrete regions on the wafer substrate.

[0131] The catalytic materials (e.g., supported or bulk) on thesubstrate are tested for activity and selectivity for the WGS reactionusing a scanning mass spectrometer (“SMS”) comprising ascanning/sniffing probe and a mass spectrometer. More details on thescanning mass spectrometer instrument and screening procedure are setforth in U.S. Pat. No. 6,248,540, in European Patent No. EP 1019947 andin European Patent Application No. EP 1186892 and corresponding U.S.application Ser. No. 09/652,489 filed Aug. 31, 2000 by Wang et al., thecomplete disclosure of each of which is incorporated herein in itsentirety. Generally, the reaction conditions (e.g. contact time and/orspace velocities, temperature, pressure, etc.) associated with thescanning mass spectrometer catalyst screening reactor are controlledsuch that partial conversions (i.e., non-equilibrium conversions, e.g.,ranging from about 10% to about 40% conversion) are obtained in thescanning mass spectrometer, for discrimination and ranking of catalystactivities for the various catalytic materials being screened.Additionally, the reaction conditions and catalyst loadings areestablished such that the results scale appropriately with the reactionconditions and catalyst loadings of larger scale laboratory researchreactors for WGS reactions. A limited set of tie-point experiments areperformed to demonstrate the scalability of results determined using thescanning mass spectrometer to those using larger scale laboratoryresearch reactors for WGS reactions. See, for example, Example 12 ofU.S. Provisional Patent Application Ser. No. 60/434,708 entitled“Platinum-Ruthenium Containing Catalyst Formulations for HydrogenGeneration” filed by Hagemeyer et al. on Dec. 20, 2002.

[0132] Preparative and Testing Procedures

[0133] The catalysts and compositions of the present invention wereidentified using high-throughput experimental technology, with thecatalysts being prepared and tested in library format, as describedgenerally above, and in more detail below. Specifically, such techniqueswere used for identifying catalyst compositions that were active andselective as WGS catalysts. As used in these examples, a “catalystlibrary” refers to an associated collection of candidate WGS catalystsarrayed on a wafer substrate, and having at least two, and typicallythree or more common metal components (including metals in the fullyreduced state, or in a partially or fully oxidized state, such as metalsalts), but differing from each other with respect to relativestoichiometry of the common metal components.

[0134] Depending on the library design and the scope of theinvestigation with respect to a particular library, multiple (i.e., twoor more) libraries were typically formed on each wafer substrate. Afirst group of test wafers each comprised about 100 different catalystcompositions formed on a three-inch wafer substrate, typically with mostcatalysts being formed using at least three different metals. A secondgroup of test wafers each comprised about 225 different catalystcompositions on a four-inch wafer substrate, again typically with mostcatalysts being formed using at least three different metals. Each testwafer itself typically comprised multiple libraries. Each librarytypically comprised binary, ternary or higher-order compositions—thatis, for example, as ternary compositions that comprised at least threecomponents (e.g., A, B, C) combined in various relative ratios to formcatalytic materials having a molar stoichiometry covering a range ofinterest (e.g., typically ranging from about 20% to about 80% or more(e.g. to about 100% in some cases) of each component). For supportedcatalysts, in addition to varying component stoichiometry for theternary compositions, relative total metal loadings were alsoinvestigated.

[0135] Typical libraries formed on the first group of (three-inch) testwafers included, for example, “five-point libraries” (e.g., twentylibraries, each having five different associated catalyst compositions),or “ten-point” libraries (e.g., ten libraries, each having ten differentassociated catalyst compositions), or “fifteen-point libraries” (e.g.,six libraries, each having fifteen different associated catalystcompositions) or “twenty-point libraries” (e.g., five libraries, eachhaving twenty different associated catalyst compositions). Typicallibraries formed on the second group of (four-inch) test wafersincluded, for example, “nine-point libraries” (e.g., twenty-fivelibraries, each having nine different associated catalyst compositions),or “twenty-five point” libraries (e.g., nine libraries, each havingtwenty-five different associated catalyst compositions). Largercompositional investigations, including “fifty-point libraries” (e.g.,two or more libraries on a test wafer, each having fifty associatedcatalyst compositions), were also investigated. Typically, thestoichiometric increments of candidate catalyst library members rangedfrom about 1.5% (e.g. for a “fifty-five point ternary”) to about 15%(e.g., for a “five-point” ternary). See, generally, for example, WO00/17413 for a more detailed discussion of library design and arrayorganization. FIGS. 6A-6F of the instant application show librarydesigns for libraries prepared on a common test wafer, as graphicallyrepresented using Library Studio® (Symyx Technologies, Inc., SantaClara, Calif.), where the libraries vary with respect to bothstoichiometry and catalyst loading. Libraries of catalytic materialsthat vary with respect to relative stoichiometry and/or relativecatalyst loading can also be represented in a compositional table, suchas is shown in the several examples of this application.

[0136] Referring to FIG. 6A, for example, the test wafer includes ninelibraries, where each of the nine libraries comprise nine differentternary compositions of the same three-component system. In thenomenclature of the following examples, such a test wafer is said toinclude nine, nine-point-ternary (“9PT”) libraries. The library depictedin the upper right hand corner of this test wafer includes catalystcompositions comprising components A, B and X₁ in 9 differentstoichiometries. As another example, with reference to FIG. 6B, apartial test wafer is depicted that includes a fifteen-point-ternary(“15PT”) library having catalyst compositions of Pt, Pd and Cu infifteen various stoichiometries. Generally, the composition of eachcatalyst included within a library is graphically represented by anassociation between the relative amount (e.g., moles or weight) ofindividual components of the composition and the relative area shown ascorresponding to that component. Hence, referring again to the fifteendifferent catalyst compositions depicted on the partial test waferrepresented in FIG. 6B, it can be seen that each composition includes Pt(red), Pd (green) and Cu (blue), with the relative amount of Ptincreasing from column 1 to column 5 (but being the same as comparedbetween rows within a given column), with the relative amount of Pddecreasing from row 1 to row 5 (but being the same as compared betweencolumns within a given row), and with the relative amount of Cudecreasing from a maximum value at row 5, column 1 to a minimum at, forexample, row 1, column 1. FIG. 6C shows a test wafer that includes afifty-point-ternary (“50PT”) library having catalyst compositions of Pt,Pd and Cu in fifty various stoichiometries. This test library could alsoinclude another fifty-point ternary library (not shown), for examplewith three different components of interest.

[0137]FIGS. 6D-6F are graphical representations of two fifty-pointternary libraries (“bis 50PT libraries”) at various stages ofpreparation—including a Pt—Au—Ag/CeO₂ library (shown as the upper rightternary library of FIG. 6E) and a Pt—Au—Ce/ZrO₂ library (shown as thelower left ternary library of FIG. 6E). Note that the Pt—Au—Ag/CeO₂library also includes binary-impregnated compositions—Pt—Au/CeO₂ binarycatalysts (row 2) and Pt-Ag/CeO₂ (column 10). Likewise, thePt—Au—Ce/ZrO₂ library includes binary-impregnatedcompositions—Pt—Ce/ZrO₂ (row 11) and Au—Ce/ZrO₂ (column 1). Briefly, thebis 50PT libraries were prepared by depositing CeO₂ and ZrO₂ supportsonto respective portions of the test wafer as represented graphically inFIG. 6D. The supports were deposited onto the test wafer as a slurry ina liquid media using a liquid handling robot, and the test wafer wassubsequently dried to form dried supports. Thereafter, salts of Pt, Auand Ag were impregnated onto the regions of the test wafer containingthe CeO₂ supports in the various relative stoichiometries as representedin FIG. 6E (upper-right-hand library). Likewise, salts of Pt, Au and Cewere impregnated onto the regions of the test wafer containing the ZrO₂supports in the various relative stoichiometries as represented in FIG.6E (lower-left-hand library). FIG. 6F is a graphical representation ofthe composite library design, including the relative amount of catalystsupport.

[0138] Specific compositions of tested catalytic materials of theinvention are detailed in the following examples for selected libraries.

[0139] Performance benchmarks and reference experiments (e.g., blanks)were also provided on each quartz catalyst test wafer as a basis forcomparing the catalyst compositions of the libraries on the test wafer.The benchmark catalytic material formulations included a Pt/zirconiacatalyst standard with about 3% Pt catalyst loading (by weight, relativeto total weight of catalyst and support). The Pt/zirconia standard wastypically synthesized by impregnating 3 μL of, for example, 1.0% or 2.5%by weight, Pt stock solution onto zirconia supports on the wafer priorto calcination and reduction pretreatment.

[0140] Typically wafers were calcined in air at a temperature rangingfrom 300° C. to 500° C. and/or reduced under a continuous flow of 5%hydrogen at a temperature ranging from about 200° C. to about 500° C.(e.g., 450° C.). Specific treatment protocols are described below withrespect to each of the libraries of the examples.

[0141] For testing using the scanning mass spectrometer, the catalystwafers were mounted on a wafer holder which provided movement in an XYplane. The sniffing/scanning probe of the scanning mass spectrometermoved in the Z direction (a direction normal to the XY plane of movementfor the wafer holder), and approached in close proximity to the wafer tosurround each independent catalyst element, deliver the feed gas andtransmit the product gas stream from the catalyst surface to thequadrupole mass spectrometer. Each element was heated locally from thebackside using a CO₂ laser, allowing for an accessible temperature rangeof about 200° C. to about 600° C. The mass spectrometer monitored sevenmasses for hydrogen, methane, water, carbon monoxide, argon, carbondioxide and krypton: 2, 16, 18, 28, 40, 44, and 84, respectively.

[0142] Catalyst compositions were tested at various reactiontemperatures, typically including for example at about 200° C., 250° C.and/or 300° C. The feed gas typically consisted of 51.6% H₂, 7.4% Kr,7.4% CO, 7.4% CO₂ and 26.2% H₂O. The H₂, CO, CO₂ and Kr internalstandards are premixed in a single gas cylinder and then combined withthe water feed. Treated water (18.1 mega-ohms-cm at 27.5° C.) producedby a Barnstead Nano Pure Ultra Water system was used, without degassing.

[0143] Data Processing and Analysis

[0144] Data analysis was based on mass balance plots where CO conversionwas plotted versus CO₂ production. The mass spectrometer signals wereuncalibrated for CO and CO₂ but were based on Kr-normalized massspectrometer signals. The software package SPOTFIRE™ (sold by SpotFire,Inc. of Somerville, Mass.) was used for data visualization.

[0145] A representative plot of CO conversion versus CO₂ production fora WGS reaction is shown in FIG. 7A involving, for discussion purposes,two ternary catalyst systems—a PtAu—Ag/CeO₂ catalyst library and aPt—Au—Ce/ZrO₂ catalyst library—as described above in connection withFIGS. 6D-6F. The catalyst compositions of these libraries were screenedat four temperatures: 250° C., 300° C., 350° C. and 400° C. Withreference to the schematic diagram shown in FIG. 7B, active and highlyselective WGS catalysts (e.g., Line I of FIG. 7B) will approach a linedefined by the mass balance for the water-gas-shift reaction (the “WGSdiagonal”) with minimal deviation, even at relatively high conversions(i.e., at CO conversions approaching the thermodynamic equilibriumconversion (point “TE” on FIG. 7B)). Highly active catalysts may beginto deviate from the WGS diagonal due to cross-over to the competingmethanation reaction (point “M” on FIG. 7C). Catalyst compositions thatexhibit such deviation may still, however, be useful WGS catalystsdepending on the conversion level at which such deviation occurs. Forexample, catalysts that first deviate from the WGS diagonal at higherconversion levels (e.g., Line II of FIG. 7B) can be employed aseffective WGS catalysts by reducing the overall conversion (e.g., bylowering catalyst loading or by increasing space velocity) to theoperational point near the WGS diagonal. In contrast, catalysts thatdeviate from the WGS diagonal at low conversion levels (e.g., Line IIIof FIG. 7B) will be relatively less effective as WGS catalysts, sincethey are unselective for the WGS reaction even at low conversions.Temperature affects the thermodynamic maximum CO conversion, and canaffect the point of deviation from the mass-balance WGS diagonal as wellas the overall shape of the deviating trajectory, since lowertemperatures will generally reduce catalytic activity. For somecompositions, lower temperatures will result in a more selectivecatalyst, demonstrated by a WGS trajectory that more closelyapproximates the WGS mass-balance diagonal. (See FIG. 7C). Referringagain to FIG. 7A, it can be seen that the Pt—Au—Ag/CeO₂ and thePt—Au—Ce/ZrO₂ catalyst compositions are active and selective WGScatalysts at each of the screened temperatures, and particularly atlower temperatures.

[0146] Generally, the compositions on a given wafer substrate weretested together in a common experimental run using the scanning massspectrometer and the results were considered together. In thisapplication, candidate catalyst compositions of a particular library onthe substrate (e.g., ternary or higher-order catalysts comprising threeor more metal components) were considered as promising candidates for anactive and selective commercial catalyst for the WGS reaction based on acomparison to the Pt/ZrO₂ standard composition included on that wafer.Specifically, libraries of catalytic materials were deemed to beparticularly preferred WGS catalysts if the results demonstrated that ameaningful number of catalyst compositions in that library comparedfavorably to the Pt/ZrO₂ standard composition included on the wafersubstrate with respect to catalytic performance. In this context, ameaningful number of compositions was generally considered to be atleast three of the tested compositions of a given library. Also in thiscontext, favorable comparison means that the compositions had catalyticperformance that was as good as or better than the standard on thatwafer, considering factors such as conversion, selectivity and catalystloading. All catalyst compositions of a given library were in many casespositively identified as active and selective WGS catalysts even insituations where only some of the library members compared favorably tothe Pt/ZrO₂ standard, and other compositions within that librarycompared less than favorably to the Pt/ZrO₂ standard. In suchsituations, the basis for also including members of the library thatcompared somewhat less favorably to the standard is that these membersin fact positively catalyzed the WGS reaction (i.e., were effective ascatalysts for this reaction). Additionally, it is noted that suchcompositions may be synthesized and/or tested under more optimally tunedconditions (e.g., synthesis conditions, treatment conditions and/ortesting conditions (e.g., temperature)) than occurred during actualtesting in the library format, and significantly, that the optimalconditions for the particular catalytic materials being tested maydiffer from the optimal conditions for the Pt/ZrO₂ standard—such thatthe actual test conditions may have been closer to the optimalconditions for the standard than for some of the particular members.Therefore, it was specifically contemplated that optimization ofsynthesis, treatment and/or screening conditions, within the generallydefined ranges of the invention as set forth herein, would result ineven more active and selective WGS catalysts than what was demonstratedin the experiments supporting this invention. Hence, in view of theforegoing discussion, the entire range of compositions defined by eachof the claimed compositions (e.g., each three-component catalyticmaterial, or each four-component catalytic material) was demonstrated asbeing effective for catalyzing the WGS reaction. Further optimization isconsidered, with various specific advantages associated with variousspecific catalyst compositions, depending on the desired or requiredcommercial application of interest. Such optimization can be achieved,for example, using techniques and instruments such as those described inU.S. Pat. No. 6,149,882, or those described in WO 01/66245 and itscorresponding U.S. applications, U.S. Ser. No. 09/801,390, entitled“Parallel Flow Process Optimization Reactor” filed Mar. 7, 2001 by Berghet al, and U.S. Ser. No. 09/801,389, entitled “Parallel Flow ReactorHaving Variable Feed Composition” filed Mar. 7, 2001 by Bergh et al.,each of which are incorporated herein by reference for all purposes.

[0147] Additionally, based on the results of screening of initiallibraries, selective additional “focus” libraries were selectivelyprepared and tested to confirm the results of the initial libraryscreening, and to further identify better performing compositions, insome cases under the same and/or different conditions. The test wafersfor the focus libraries typically comprised about 225 differentcandidate catalyst compositions formed on a four-inch wafer substrate,with one or more libraries (e.g. associated ternary compositions A, B,C) formed on each test wafer. Again, the metal-containing components ofa given library were typically combined in various relative ratios toform catalysts having stoichiometry ranging from about 0% to about 100%of each component, and for example, having stoichiometric increments ofabout 10% or less, typically about 2% or less (e.g., for a “fifty-sixpoint ternary”). Focus libraries are more generally discussed, forexample, in WO 00/17413. Such focus libraries were evaluated accordingto the protocols described above for the initial libraries.

[0148] The raw residual gas analyzer (“rga”) signal values generated bythe mass spectrometer for the individual gases are uncalibrated andtherefore different gases may not be directly compared. Methane data(mass 16) was also collected as a control. The signals are typicallystandardized by using the raw rga signal for krypton (mass 84) to removethe effect of gas flow rate variations. Thus, for each library element,the standardized signal is determined as, for example, sH₂O=raw H₂O/rawKr; sCO=raw CO/raw Kr; sCO₂=raw CO₂/raw Kr and so forth.

[0149] Blank or inlet concentrations are determined from the average ofthe standardized signals for all blank library elements, i.e. libraryelements for which the composition contains at most only support. Forexample, b_(avg) H₂O=average sH₂O for all blank elements in the library;b_(avg) CO=average sCO for all blank elements in the library; and soforth.

[0150] Conversion percentages are calculated using the blank averages toestimate the input level (e.g., b_(avg) CO) and the standardized signal(e.g., sCO) as the output for each library element of interest. Thus,for each library element, CO_(conversion)=100×(b_(avg) CO−sCO)/b_(avg)CO and H₂O_(conversion)=100×(b_(avg) H₂O−sH₂O)/b_(avg) H₂O.

[0151] The carbon monoxide (CO) to carbon dioxide (CO₂) selectivity isestimated by dividing the amount of CO₂ produced (sCO₂−b_(avg) CO₂) bythe amount of CO consumed (b_(avg) CO−sCO). The CO₂ and CO signals arenot directly comparable because the rga signals are uncalibrated.However, an empirical conversion constant (0.6 CO₂ units=1 CO unit) hasbeen derived, based on the behavior of highly selective standardcatalyst compositions. The selectivity of the highly selective standardcatalyst compositions approach 100% selectivity at low conversion rates.Therefore, for each library element, estimated CO to CO₂selectivity=100×0.6×(sCO₂−b_(avg) CO₂)/(b_(avg) CO−sCO). Low COconsumption rates can produce highly variable results, and thus thereproducibility of CO₂ selectivity values is maintained by artificiallylimiting the CO₂ selectivity to a range of 0% to 140%.

[0152] The following examples are representative of the screening oflibraries that lead to identification of the particularly claimedinventions herein.

EXAMPLE 1

[0153] A 4″ quartz wafer was pre-coated with 15 different carriers byslurry dispensing as master batches. The carrier deposition was carriedout with the following carriers: SiO₂ (PQ-MA 1620), WSI₂ 99.5%, SiO₂(80:20 mixture of SiO₂ Kieselgur:BASF), SiO₂ (Aerosil 200), SiO₂(KA160), SiO₂ (SS5131), SiO₂ (Condea Siralox 5/150), SiO₂ (NortonXS16080), SiO₂ (Engelhard Siliperl AF125), SiO₂ LSA, γ-Al₂O₃ CataloxSBa-150, V-doped sol-gel zirconia (Norton XZ16052) PtCe masterbatches 1and 2. Each slurry was composed of 1 g of carrier in 4 mL of a 50:50ethylene glycol(“EG”):H₂O mixture, except for SiO₂ PQ-MA 1620 which wasprepared by adding 1 g carrier to 8 mL EG/H₂O, 50:50 and ZrO₂ Xz16052which was prepared by adding 1.5 g to 4 mL of EG/H₂O/methyl oxide(“MEO”), 32.5:30:37.5.

[0154] Approximately 3 μL of each carrier slurry was dispensed to avertical 15 point column on the wafer. After the completion of thedispensing step of columns 1-15, the samples were oven-dried at 70° C.for 10 minutes. Six internal standards were synthesized by spotting 3 μLof a Pt(NH₃)₂(NO₂)₂ stock solution (2.5% Pt) into the correspondingfirst row/last column positions.

[0155] The carriers were then impregnated with an 2×7 point singlecolumn 1M NaOH gradient from top to bottom by first Cavro dispensingfrom the corresponding stock solution vial to the microtiter plate anddiluting with distilled water. A replica transfer of the microtiterplate pattern to the wafer followed (2.5 μL dispense volume per well),resulting in two 7×15 point rectangles on the wafer with row no. 9 notimpregnated with NaOH.

[0156] The wafer was then dried at room temperature for 2 hours andoven-dried for 2 minutes. The last impregnation was a uniform dispensing(2.5 μL dispense volume per well, resulting a 15×15 point rectangle)from the stock solution vial Pt(NH₃)₂(NO₂)₂ (1% Pt) to the wafer.

[0157] The wafer was dried at room temperature for 2 hours and reducedin 5% H₂₁N₂ at 200° C. for 2 hours. Commercial catalyst was slurriedinto 5 positions of the first row and last column as an externalstandard (3 μL). See FIGS. 1A-1D.

[0158] The reduced library was then screened by scanning massspectrometry for WGS activity with a H₂/CO/CO₂/H₂O mixed feed at 200°C., 230° C. and 260° C. See FIGS. 1E-1G.

[0159] This experiment demonstrated active and selective WGS catalystformulations of various Pt and Na catalyst formulations on varioussilica, alumina and zirconia carriers. Of particular interest were thePt—Na formulations on two silicas, Engelhard Siliperl AF125 and CondeaSiralox 5/150, and a γ-alumina, Condea Catalox SBa-150 which showedhigher activity than ZrO₂ supported Pt—Na in the temperature range of230° C. to 260° C.

EXAMPLE 2

[0160] A 4″ quartz wafer was precoated with a γ-Al₂O₃ (Catalox Sba-150)carrier by slurry dispensing 3 μL (1 g of γ-Al₂O₃ in 4 mL of EG/H₂O,50:50) to each element of a 15×15 square on the wafer. The wafer wasthen oven-dried at 70° C. for 12 minutes.

[0161] Six internal standards were synthesized by Cavro spotting 3 μL ofa Pt(NH₃)₂(NO₂)₂ (2.5% Pt) stock solution into the corresponding firstrow/last column positions. The wafer was impregnated with a uniform Ptlayer by dispensing into columns C1 to C5 (2.5 μL per well) a stocksolution of Na₂Pt(OH)₆ (from powder, 1% Pt) to the wafer.

[0162] Columns C6 to C15 of the wafer were then impregnated withfollowing metal-gradients from top to bottom: ZrO(NO₃)₂, La(NO₃)₃,Y(NO₃)₃, Ce(NO₃)₃, H₂MoO₄, Fe(NO₃)₃, Co(NO₃)₂, ZrO(OAc)₂, Mn(NO₃)₂ andKRuO₄ by Cavro dispensing from the respective stock solution vials to amicrotiter plate and diluted with distilled water. A replica transfer ofthe microtiter plate pattern to the wafer followed (2.5 μL dispensevolume per well), resulting in a 10×15 point rectangle on the wafer (10columns with metal gradients).

[0163] The wafer was dried for 3.5 hours at room temperature and thencoated with base gradients (0.5M, opposing gradients) includingCsOH—NaOH, LiOH—NaOH, RbOH—NaOH and KOH—NaOH separately in each of thefirst four columns, respectively, and NaOH in columns 5 to 15 (1M basewith a gradient from bottom to top) by Cavro dispensing from thecorresponding stock solution vials to the microtiter plate and dilutingwith distilled water. A replica transfer of the microtiter plate patternto the wafer followed (2.5 μL dispense volume per well), resulting in a15×15 point rectangle on the wafer (15 columns with base gradients). Thewafer was dried overnight at room temperature and oven-dried for 2minutes.

[0164] The final impregnation was a uniform dispensing (2.5 μL dispensevolume per well, resulting a 10×15 point square) from a stock solutionvial of Na₂Pt(OH)₆ (from powder, 1% Pt) to columns 6 through 15 of thewafer as a ternary layer. Commercial catalyst was slurried into 5positions of the first row and last column as an external standard (3μL).

[0165] The wafer was dried at room temperature for 4 hours and thencalcined in air at 450° C. for 2 hours followed by reduction with 5%H₂/N₂ at 250° C. for 2 hours. See FIGS. 2A-2C.

[0166] The library was screened by SMS for WGS activity with aH₂/CO/CO₂/H₂O mixed feed at 200° C., 230° C. and 260° C.

[0167] This experiment demonstrated active and selective WGS catalystformulations of various Pt—Na—{Li, K, Rb, Cs} catalyst formulations onalumina and a synergistic effect between Li—Na binary combinations.

EXAMPLE 3

[0168] A 4″ quartz wafer was precoated with five commercial catalysts(supplied by Alfa Aesar and Aldrich) by slurry dispensing of catalystpowder (preformed commercial catalysts: Ir 1%/γ-Al₂O₃ (reduced), Ir5%/CaCO₃, Pd 0.5%/γ-Al₂O₃, Pd 5%/BaCO₃ (reduced), Ru 5%/γ-Al₂O₃(reduced), each slurry prepared from 1.5 g catalyst in 4 mL ofEG/H₂O/MEO 32.5:30:37.5). Each carrier solution was dispensed into 3different columns at intervals of 5 columns. The wafer was then ovendried for 12 min at 70° C. Six internal standards were synthesized byspotting 3 μL of Pt(NH₃)₂(NO₂)₂ stock solution (2.5% Pt) into thecorresponding first row/last column positions. The wafer was thenimpregnated with 15-point dopant gradients of 2 columns NaOH (1M) and 1column Pt(NH₃)₂(NO₂)₂ (2%) by Cavro dispensing from 2 stock solutionvials to a microtiter plate followed by a transfer of the microtiterplate pattern onto the wafer (2.5 μL dispense volume per well, 5replicas of each column resulting in three 5×15 rectangles on thewafer).

[0169] The wafer was dried at room temperature for 2 hours and then 5columns were impregnated with a reverse 15-point dopant gradient ofPt(NH₃)₄(OH)₂ (2%) by Cavro dispensing from stock solution vial to amicrotiter plate, followed by a transfer of the 15P microtiter platecolumn (Pt gradient) onto the wafer (2.5 μL dispense volume per well, 5replicas of the 15P Pt gradient resulting in a 5×15 rectangle on thewafer).

[0170] The wafer was dried at room temperature for 2 hours, reduced in aflow of 5% H₂/N₂ at 250° C. for 2 hours. Commercial catalyst wasslurried into five positions of the first row and last column asexternal standard (3 μL catalyst slurry). See FIGS. 3A-3D.

[0171] The reduced library was then screened by SMS for WGS activitywith a H₂/CO/CO₂/H₂O mixed feed at 200° C., 250° C. and 300° C. SeeFIGS. 3E and 3F.

[0172] This experiment demonstrated active and selective WGS catalystformulations of various Ru—Na catalyst formulations on alumina.

EXAMPLE 4

[0173] Scale-up catalyst samples were prepared by using incipientwetness impregnation of 0.75 grams of ZrO₂ support (Norton, 80-120 mesh)which had been weighed into a 10 dram vial. Aqueous metal precursor saltsolutions were then added in the order Pt, one of Li, K, or Na. Theprecursor salt solutions were tetraammineplatinum (II) hydroxidesolution (9.09% Pt (w/w)), lithium hydroxide monohydrate (2.5M),potassium hydroxide (13.92% K (w/w)), and sodium hydroxide (3.0N). Allstarting reagents were nominally research grade purchased from Aldrich,Strem, or Alfa. Following each metal addition, the catalysts were driedat 80° C. overnight and then calcined in air as follows:

[0174] After Pt addition—300° C. for 3 hours

[0175] After Na, Li, or K addition—300° C. for 3 hours

[0176] Following final addition, the catalysts were reduced in-situ at300° C. for 3 hours in a 10% H₂/N₂ feed.

[0177] Catalyst Testing Conditions

[0178] Catalysts were tested in a fixed bed reactor. Approximately 0.15g of catalyst was weighed and mixed with an equivalent mass of SiC. Themixture was loaded into a reactor and heated to reaction temperature.Reaction gases were delivered via mass flow controllers (Brooks) withwater introduced with a metering pump (Quizix). The composition of thereaction mixture was as follows: H₂ 50%, CO 10%, CO₂ 10%, and H₂O 30%.The reactant mixture was passed through a pre-heater before contactingthe catalyst bed. Following reaction, the product gases were analyzedusing a micro gas chromatograph (Varian Instruments, or Shimadzu).Compositional data on the performance diagram (FIG. 4) is on a dry basiswith water removed.

[0179] Testing Results

[0180]FIG. 4 shows the CO composition in the product stream followingthe scale-up testing at a gas hour space velocity of 50,000 h⁻¹. TABLE 1Catalyst Compositions (mass ratio) Row Col Support K Pt Li Na A 1 0.9250.015 0.06 0 0 A 2 0.91 0.03 0.06 0 0 A 3 0.895 0.045 0.06 0 0 A 4 0.880.06 0.06 0 0 A 5 0.865 0.075 0.06 0 0 A 6 0.85 0.09 0.06 0 0 B 1 0.9250 0.06 0.0148 0 B 2 0.911 0 0.06 0.0292 0 B 3 0.897 0 0.06 0.0432 0 B 40.883 0 0.06 0.0567 0 B 5 0.870 0 0.06 0.0698 0 B 6 0.857 0 0.06 0.08250 C 1 0.89 0.01 0.06 0 0.04 C 2 0.89 0.016 0.06 0 0.034 C 3 0.89 0.0220.06 0 0.028 C 4 0.89 0.028 0.06 0 0.022 C 5 0.89 0.034 0.06 0 0.016 C 60.89 0.04 0.06 0 0.01 D 1 0.89 0 0.06 0.01 0.04 D 2 0.89 0 0.06 0.0160.034 D 3 0.89 0 0.06 0.022 0.028 D 4 0.89 0 0.06 0.028 0.022 D 5 0.89 00.06 0.034 0.016 D 6 0.89 0 0.06 0.04 0.01

EXAMPLE 5

[0181] Scale-up catalyst samples were prepared by using incipientwetness impregnation of 0.75 grams of ZrO₂ support (Norton, 80-120 mesh)which had been weighed into a 10 dram vial. Aqueous metal precursor saltsolutions were then added in the order: Re, Pt, and one of Na, K, or Li.The precursor salt solutions were tetraammineplatinum (II) hydroxidesolution (9.09% Pt (w/w)), perrhenic acid (Re 10% (w/w)), sodiumhydroxide (3.0N), potassium hydroxide (13.92% K w/w)), and lithiumhydroxide monohydrate (2.5M). All starting reagents were nominallyresearch grade purchased from Aldrich, Strem, or Alfa. Following eachmetal addition, the catalysts were dried at 80° C. overnight and thencalcined in air as follows:

[0182] After Pt addition—300° C. for 3 hours

[0183] After Re addition—450° C. for 3 hours

[0184] Following Na, K, or Li addition, the catalysts were calcined at300° C. for 3 hours, and then the catalysts were reduced in-situ at 300°C. for 3 hours in a 10% H₂₁N₂ feed.

[0185] Catalyst Testing Conditions

[0186] Catalysts were tested in a fixed bed reactor. Approximately 0.15g of catalyst was weighed and mixed with an equivalent mass of SiC. Themixture was loaded into a reactor and heated to reaction temperature.Reaction gases were delivered via mass flow controllers (Brooks) withwater introduced with a metering pump (Quizix). The composition of thereaction mixture was as follows: H₂ 50%, CO 10%, CO₂ 10%, and H₂O 30%.The reactant mixture was passed through a pre-heater before contactingthe catalyst bed. Following reaction, the product gases were analyzedusing a micro gas chromatograph (Varian Instruments, or Shimadzu).Compositional data on the performance diagram (FIG. 5) is on a dry basiswith water removed.

[0187] Testing Results

[0188]FIG. 5 shows the CO composition in the product stream followingthe scale-up testing at a gas hour space velocity of 50,000 h⁻¹. TABLE 2Catalyst Compositions (mass ratio) Row Col Support Pt Re Na K Li A 10.905 0.06 0.02 0.015 0 0 A 2 0.89 0.06 0.02 0.03 0 0 A 3 0.875 0.060.02 0.045 0 0 A 4 0.885 0.06 0.04 0.015 0 0 A 5 0.87 0.06 0.04 0.03 0 0A 6 0.855 0.06 0.04 0.045 0 0 B 1 0.905 0.06 0.02 0 0.015 0 B 2 0.890.06 0.02 0 0.03 0 B 3 0.875 0.06 0.02 0 0.045 0 B 4 0.885 0.06 0.04 00.015 0 B 5 0.87 0.06 0.04 0 0.03 0 B 6 0.855 0.06 0.04 0 0.045 0 C 10.915 0.06 0.02 0 0 0.005 C 2 0.91 0.06 0.02 0 0 0.01 C 3 0.905 0.060.02 0 0 0.015 C 4 0.895 0.06 0.04 0 0 0.005 C 5 0.89 0.06 0.04 0 0 0.01C 6 0.885 0.06 0.04 0 0 0.015 D 1 0.955 0 0.02 0.025 0 0 D 2 0.93 0 0.020.05 0 0 D 3 0.935 0 0.04 0.025 0 0 D 4 0.91 0 0.04 0.05 0 0 D 5 0.915 00.06 0.025 0 0 D 6 0.89 0 0.06 0.05 0 0

EXAMPLE 6

[0189] Scale-up catalyst samples were prepared by using incipientwetness impregnation of 0.75 grams of ZrO₂ support (Norton, 80-120 mesh)which had been weighed into a 10 dram vial. Aqueous metal precursor saltsolutions were added, first Pt and than Na at the following weightpercent levels: zero, 1.5, 3.0, 4.5, 6.0, 7.5, and 9.0. The precursorsalt solutions were tetraammineplatinum (II) hydroxide solution (9.09%Pt (w/w)) and sodium hydroxide (3.0N). All starting reagents werenominally research grade purchased from Aldrich, Strem, or Alfa.Following each metal addition, the catalysts were dried at 80° C.overnight and then calcined in air as follows:

[0190] After Pt addition—300° C. for 3 hours

[0191] Following Na addition, the catalysts were calcined at 300° C. for3 hours, and then the catalysts were reduced in-situ at 300° C. for 3hours in a 10% H₂/N₂ feed.

[0192] Catalyst Testing Conditions

[0193] Catalysts were tested in a fixed bed reactor. Approximately 0.15g of catalyst was weighed and mixed with an equivalent mass of SiC. Themixture was loaded into a reactor and heated to reaction temperature.Reaction gases were delivered via mass flow controllers (Brooks) withwater introduced with a metering pump (Quizix). The composition of thereaction mixture was as follows: H₂ 50%, CO 10%, CO₂ 10%, and H₂O 30%.The reactant mixture was passed through a pre-heater before contactingthe catalyst bed. Following reaction, the product gases were analyzedusing a micro gas chromatograph (Varian Instruments, or Shimadzu).Compositional data on the performance diagram (FIG. 8) is on a dry basiswith water removed.

[0194] Testing Results

[0195]FIG. 8 shows the CO composition in the product stream followingthe scale-up testing at a gas hour space velocity of 50,000 h⁻¹.

What we claim is:
 1. A method for producing a hydrogen-rich gas whichcomprises: contacting a carbon monoxide containing gas with a water gasshift catalyst in the presence of water at a temperature of less thanabout 260° C., wherein the water gas shift catalyst comprises: a) atleast one of Pt, Ru, their oxides and mixtures thereof; and b) Na, itsoxides or mixtures thereof.
 2. A method according to claim 1, whereinthe water gas shift catalyst further comprises Li, its oxides ormixtures thereof.
 3. A method according to claim 1, wherein the watergas shift catalyst comprises: a) Pt, its oxides or mixtures thereof; andb) Na, its oxides or mixtures thereof.
 4. A method according to claim 1,wherein the water gas shift catalyst comprises: a) Ru, its oxides ormixtures thereof; and b) Na, its oxides or mixtures thereof.
 5. A methodaccording to claim 1, wherein the carbon monoxide containing gas is asyngas.
 6. A method according to claim 2, wherein the water gas shiftcatalyst comprises: a) Pt, its oxides or mixtures thereof; b) Na, itsoxides or mixtures thereof; and c) Li, its oxides or mixtures thereof.7. A method according to claim 2, wherein the water gas shift catalystcomprises: a) Ru, its oxides or mixtures thereof; b) Na, its oxides ormixtures thereof, and c) Li, its oxides or mixtures thereof.
 8. A methodaccording to claim 1, wherein the water gas shift catalyst is supportedon a carrier comprising at least one member selected from the groupconsisting of alumina, zirconia, titania, ceria, magnesia, lanthania,niobia, yttria and iron oxide, and mixtures thereof.
 9. A methodaccording to claim 8, wherein the alumina is doped with Zr.
 10. A methodaccording to claim 8, wherein the carrier comprises zirconia.
 11. Amethod according to claim 1, wherein the carbon monoxide containing gasis contacted with the water gas shift catalyst at a pressure of no morethan about 50 bar.
 12. A method according to claim 11, wherein thecarbon monoxide containing gas is contacted with the water gas shiftcatalyst at a pressure of no more than about 15 bar.
 13. A methodaccording to claim 11, wherein the carbon monoxide containing gas iscontacted with the water gas shift catalyst at a pressure of no morethan about 1 bar.
 14. A method according to claim 1, wherein the watergas shift catalyst comprises about 0.05 wt. % to about 10 wt. %, withrespect to the total weight of all catalyst components plus the supportmaterial, of Pt or Ru present in the water gas shift catalyst.
 15. Amethod according to claim 14, wherein the water gas shift catalystcomprises about 0.50 wt. % to about 6 wt. %, of Pt or Ru present in thewater gas shift catalyst.
 16. A catalyst for catalyzing the water gasshift reaction at a temperature of less than about 260° C. comprising:a) at least one member selected from the group consisting of Pt, Ru,their oxides and mixtures thereof, and b) at least one member selectedfrom the group consisting of Na, its oxides and mixtures thereof.
 17. Acatalyst according to claim 16, wherein the catalyst further comprisesLi, its oxides, or mixtures thereof.
 18. A catalyst according to claim16, wherein the source of the Na is NaOH, Na₂CO₃ or NaHCO₃.
 19. Acatalyst according to claim 17, wherein the source of the Li is LiOH.20. A catalyst according to claim 16 comprising: a) Pt, its oxides ormixtures thereof, and b) Na, its oxides or mixtures thereof.
 21. Acatalyst according to claim 16 comprising: a) Ru, its oxides or mixturesthereof, and b) Na, its oxides or mixtures thereof.
 22. A catalystaccording to claim 17 comprising: a) Pt, its oxides or mixtures thereof,b) Na, its oxides or mixtures thereof, and c) Li, its oxides or mixturesthereof.
 23. A catalyst according to claim 17 comprising: a) Ru, itsoxides or mixtures thereof, b) Na, its oxides or mixtures thereof, andc) Li, its oxides or mixtures thereof.
 24. A catalyst according to claim16, wherein the catalyst composition is supported on a carriercomprising at least one member selected from the group consisting ofalumina, silica, zirconia, titania, ceria, magnesia, lanthania, niobia,yttria and iron oxide, and mixtures thereof.
 25. A catalyst according toclaim 24, wherein the carrier comprises zirconia, alumina or silica. 26.A catalyst according to claim 24, wherein the water gas shift catalystcomprises about 0.05 wt. % to about 10 wt. %, with respect to the totalweight of all catalyst components plus the support material, of Pt or Rupresent in the water gas shift catalyst.
 27. A catalyst according toclaim 26, wherein the water gas shift catalyst comprises about 0.50 wt.% to about 6 wt. %, of Pt or Ru present in the water gas shift catalyst.28. A fuel processing system for generation of a hydrogen-rich gas froma hydrocarbon or substituted hydrocarbon fuel, the fuel processingsystem comprising: a fuel reformer for converting a fuel reactant streamcomprising a hydrocarbon or a substituted hydrocarbon fuel to a reformedproduct stream comprising carbon monoxide and water, the fuel reformerhaving an inlet for receiving the reactant stream, a reaction chamberfor converting the reactant stream to the product stream and an outletfor discharging the product stream; a water gas shift reactor foreffecting a water gas shift reaction at a temperature of less than about260° C., the water gas shift reactor comprising an inlet for receiving awater gas shift feed stream comprising carbon monoxide and water fromthe product stream of the fuel reformer, a reaction chamber comprisingthe water gas shift catalyst of claim 16, the water gas shift catalystbeing effective for generating hydrogen and carbon dioxide from thewater gas shift feed stream and an outlet for discharging the resultinghydrogen-rich gas; and a temperature controller adapted for maintainingthe temperature of the reaction chamber of the water gas shift reactorat a temperature of less than about 300° C.